It is estimated that 30 million people, mostly of African descent, possess the gene for sickle cell disease (SCD). Recently, the drug hydroxyurea (HU) has been suggested for the treatment of sickle cell disease. HU apparently works by increasing the levels of fetal hemoglobin (Hb F) in the recipient. There are a number of other acquired and inherited conditions in which Hb F levels are increased in adults, such as some thalassemias (of which there are over 150 million carriers) and leukemias. The present methods used to measure Hb F, such as alkaline denaturation and HPLC, are not suitable for a large amount of samples. In Phase I we developed several prototype ELISAs capable of quantitating Hb F, as well as a flow cytometry-based procedure which identify Hb F-containing cells. One of these ELISAs is bloodspot based, allowing for easy collection/storage of samples. In Phase II, we will refine the ELISA assays, increasing the number of samples/plate and format them to either colorometric or fluorescent detection. The flow cytometry test will also be refined and used to identify Hb F containing cells in sickle cell patients, as well as identify fetal cells in maternal circulation. PROPOSED COMMERCIAL APPLICATION: Thirty million people worldwide possess the gene for sickle call disease. In addition, 100,000 cases of Beta- thalassemia are reported yearly. Recently, the compound hydroxyurea has been demonstrated to ease the symptoms of sickle cell disease by increasing the levels of fetal hemoglobin (Hb F) in these patients, Commercial kits could determine the % HbF and the number of red cells and reticulocytes containing Hb F in sickle cell and Beta-thalassemia patients prior to and during drug treatment. This data will aid in evaluating the performance of various drug treatments. Once these drugs are accepted for widespread use, a simple test will be needed to evaluate a large number of samples. These tests could prove useful in determining fetal-maternal hemorrhage.